This invention relates generally to a printer head and more particularly to a dot printer head used to print on paper by means of a plurality of needles impacting on paper through an ink ribbon. Various structures for mechanical dot printer heads have been developed. In the prior art the needle is frequently directly attached to the armature of a solenoid and the distance that the wire is moved equals the distance that the solenoid armature is moved. The greater the distance of armature movement, the greater is the power required to operate the solenoid and the physical size of the solenoid is also increased. A common deficiency in the prior art is that the gap between an attracted surface of the movable element connected to the needle and the attracting surface of a fixed iron core of the electromagnetic solenoid, cannot be reduced by any low priced production method. Dot printer heads are expensive becauase some heads need very high precision in production, and some dot printer heads require complex adjustment of the magnetic gap for reliable operation. When low-priced dot printer heads are produced, the gap is large and more energy is required for supplying the electromagnetic coil than the electromagnet would otherwise need in order to perform the function of printing with high quality. Large solenoids also generate a high level of heat during operation. This heat must be dissipated.
What is needed is a dot printer head which drives the printing needles with solenoids having very small magnetic gaps. Good impact velocity combined with a long needle stroke is also desirable. The gap should need no adjustment and remain fixed.